Well casing is made up of casing joints and well casing collars for connecting the casing joints together to assemble a casing string. Well casing is commonly used to line recently drilled hydrocarbon wellbores to prevent borehole collapse and provide a smooth conduit for inserting tools required to complete the well for production and produce hydrocarbon from the well. Most hydrocarbon wells drilled today are vertical bores extending down to proximity of a hydrocarbon production zone and horizontal bores within the production zone. The vertical and the horizontal bores are cased in a manner well known in the art after they are drilled. The cased bore must be “completed” before hydrocarbon production can commence. Completing a cased well bore generally involves opening ports through the casing, followed by stimulating the production zone that surrounds the open casing ports by injecting high pressure fracturing fluids through the casing and into the formation. There are many known methods used to complete a cased well bore but only a few, such, as the openhole multistage system and plug-and-perf system, have achieved large-scale commercial success. All known methods of cased well completion suffer from certain drawbacks that are well understood by those skilled in the art.
Applicant's U.S. patent application Ser. No. 15/469,821 filed Mar. 27, 2017 and entitled Pressure Perforated Well Casing System describes a well casing system that overcomes many of the problems associated with the completion of cased well bores. In Applicant's well, casing system, pressure perforated well casing joints and/or pressure perforated well casing collars are assembled into a casing string that is inserted into a well bore and pressure perforated using high pressure fluid pumped from the surface after the casing string has been cemented in the well bore. However, additional research has now shown that even further improvements are achievable.
There therefore exists a need for a novel well casing collar that is pressure perforated after it is assembled in a well casing string that is inserted and cemented into a section of a recently drilled wellbore.